Specially formulated cleaner contains Sporex a unique additive which removes tough stains from mildew, mold, algae, fungus, and moss. Restores the original look to wood decks and fences. Dissolves the toughest stains from dirt, oil, grease, bird droppings, tree sap, and acid rain. Great to use on composite decks. Earth friendly: Water-based, biodegradable, nonflammable, nontoxic, nonabrasive formula. 1 gallon of concentrate makes 11 gallon. Covers up to 2000 sq. ft.